The ghost lights seen between galaxies are very old, created when countless stars wander intergalactically like lost, spirits, emitting a ghostly haze of light. The stars emitting the ghostly haze are not gravitationally bound to any one galaxy in a cluster, troubling astronomers with the question of how the stars become so scattered throughout the cluster.
Several theories include the possibility that the stars were thrown around after the galaxies merged, or that they existed in the formative years of a cluster several billion years ago. Hubble’s infrared survey sheds light on the mystery of “intracluster light”, new observations suggest that these stars have been drifting around for billions of years, and are not the product of recent dynamical activity inside a galaxy cluster.
Hubble images two massive clusters of galaxies, named MOO J1014+0038 (left panel) and SPT-CL J2106-5844 (right panel), to detect a smooth distribution of light from stray stars scattered across the faintly glowing cluster captured. The blue color seen in the image is translated from Hubble data, research suggests that stars were ejected from their parent galaxies billions of years ago, and are now drifting through space.
The researchers included 10 galaxy clusters for the study, and which are about 10 billion light-years away, their faint intracluster light is 10,000 times fainter than in the night sky, so that they can be seen from the ground. The research found that the fraction of intracluster light relative to total light in the cluster is constant, says James Gee of Yonsei University in Seoul, South Korea, These stars were already homeless in the early stages of cluster formation.